Divergent Synthesis of Tunable Cyclopentadienyl Ligands and Their Application in Rh-Catalyzed Enantioselective Synthesis of Isoindolinone

A series of rhodium complexes bearing sterically and electronically tunable cyclopentadienyl ligands, prepared by utilizing Co2(CO)8-mediated [2+2+1] cyclization as a key step, were synthesized. In the presence of 2.5 mol% of CpmRh4, unprecedented enantio­selective [4+1] annulation reaction of benzamides and alkenes was achieved with a broad substrate scope under mild reaction conditions, providing a variety of isoindolinones with excellent regio- and enantio­selectivity (up to 94% yield, 97:3 er). Preliminary mechanistic studies suggest that the reaction involves an oxidative Heck reaction and an intra­molecular enantio­selective alkene hydro­amination reaction.